Malibu Speed Control vs Zero Off

[2h20fn]

Hello

i am trying to understand the Malibu Speed Control. I thought it uses the paddle wheel to determine speed. I am on a river so GPS doesn’t account for current.  When I have the Malibu speed control set and go under a bridge the boat accelerates rapidly for a brief moment then settles back down.  I am wondering why. 
 

Thanks

[UWSkier]

What's the water doing under that bridge?  If it's swirling around due to the supports, the speed might be reading low for a bit.  Watch the display sometime and see what it says.

[dalt1]

My 18 LSV would have a slight accel bump. Always thought it was strange that it defaults to higher speed than lower. My new Supra SL does the same. Any bridge I go under is at most 2 lanes wide, if it was a 8 lane bridge, would it just keep accelerating till the other side?   

[Woodski]

One clue would be a GPS puck.  Quick test - use your phone, download a speed app then you can do a speed compare going upstream v downstream and see if there is the expected difference.  Agree with @UWSkier the current is disturbed under the bridge, are there pillars in the water, they tend to disturb the flow.

[mxmark4]

My moomba does it with zero off but I always thought it was where I come at it from an angle and I am turning so it applies more throttle as I cut thru.